I.L. 40-386.4
1-6
tion from the remote terminal. The remote terminal recognizes the loss of load-current in the
unfaulted phase(s) as evidence of tripping of the remote breaker. This, coupled with Zone-2 dis-
tance or directional overcurrent ground-fault recognition at the remote terminal, allows immedi-
ate tripping to take place at that terminal by bypassing the remaining zone 2 delay time.
1.4.4
Self-checking Software
REL301/302 continuously monitors its ac input subsystems using multiple A/D converter cali-
bration-check inputs, plus loss-of-potential and loss-of-current monitoring. Failures of the A/D
converter or any problem in a single ac channel, which unbalances non-fault inputs, causes an
alarm and blocks tripping. Self-checking software includes the following functions:
a. A/D Converter Check
b. Program Memory Checksum
Immediately upon power-up, the relay does a complete EPROM checksum of program
memory. After power-up, the REL301/302 continually computes the program memory
checksum.
c.
Power-up Volatile RAM Check
Immediately upon power-up, the relay does a complete test of the RAM data memory. After
power-up, the REL301/302 continually performs the RAM check.
d. Non-volatile RAM Check
All front-panel-entered constants (settings) are stored in non-volatile RAM in three identical
arrays. These arrays are continuously checked by the program. If any of the three array
entrees disagree, a non-volatile RAM failure is detected.
1. 5.
UNIQUE REMOTE COMMUNICATION PROGRAM (RCP)
Special remote communications software, RCP is provided for obtaining fault, metering and cur-
rent settings data as well as sending data to the REL301/302. RCP can best be described as a
user friendly way of using a personal computer (PC) to communicate with ABB protective relays
by way of pull-downs menus. By coupling a computer with the appropriate communications
hardware, it is possible to perform all relay setting and data interactions that are possible from
the man-machine interface. RCP is
required to communicate with the REL301/302 via the com-
munication port(s). Refer to RCP instruction manual, I.L. 40-603, for detailed information.
1.5.1
ABB Bulletin Board
The ABB Relay Division Bulletin Board (BBS) is now on line. To obtain the latest version of RCP
software, please call the ABB BBS via modem at:
(800) 338-0581 or (954) 755-3250
Using configuration settings 300-14,400 bits/second, 8 data bits, 1 stop bit, no parity and full
duplex. Once the connection is established and login is completed, choose L - Library of Files
from the TOP menu. Next, select D - Down Load File, from the Library of Files, RCPxxx.EXE
(where xxx is the most recent version number e.g. 181 for version 1.81). RCPxxx.EXE is a com-
pressed, self extracting file which is expanded and installed by simply typing RCPxxx and fol-
lowing the instructions.